I'd use a standard dry fly hook with fine wire. Sometimes use 2x long shank hooks but not necessary. Dry fly hooks with fine wire in really any brand are great, though you'll have a tough time beating the price at Allen Fly Fishing.

As for hackle, look for dry fly capes or saddles. Personally I get most of mine from the Feather Emporium (online) but local shops and other online stores will carry dry fly hackle. Can get 100 packs but with commonly used colors like brown and grizzle you're better off in the long run getting a saddle or cape.

The wings should be about the length of the hook shank
If you make the wing(s) too large the fly will twist the tippet. If you make them small they won't be seen by the trout and you might as well skip them altogether.
When a dry fly floats into the trout's "window" the first thing seen is the wing and that may be what "triggers" the strike.

(I make the wing on many of my dry flies out of poly yarn and trim them to size as a last step. You never get it wrong that way )

Rip Tide is correct in that the wing of a dry fly should be the length of the hook shank. However for an Adams, I have not found that to be the case. The tails fibers and hackle on a standard dry fly are the length of the hook shank. The wings on an Adams need to be longer so that they stand up above the hackle.

Here is a photo of an Adams from Charlie Craven's article on dry fly proportion. He says the wing should be the length of the hook shank.

However if you actually measure the wing on this fly, it is longer than the hooks shank. The hook shank length is from the back of the hook eye to where the shank starts to bend. It is the straight part of the hook without the hook eye to where the fly body ends.

Take a sheet of paper, put it on your computer screen and actually measure the length of the hook shank from the hook eye to the end of the fly body and compare it to the length of the wings. The wings are longer than the hook shank.